SBQ 2423

Type of Estimation RatesType of Estimation Rates

FARA DIVA MUSTAPA

DEPARTMENT OF QUANTITYDEPARTMENT OF QUANTITY SURVEYING, FACULTY OF BUILT 

ENVIRONMENTO

General rule in estimating processGeneral rule in estimating process

FORECASTINGFORECASTING COMPARISONCOMPARISONvolv

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FORECASTINGFORECASTING

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ANALYSISANALYSISBALANCINGBALANCING

ForecastingForecasting

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Inv Information such as:

- Cost per m2 for various type of buildingElemental unit rates

Information such as:- Cost per m2 for various type of building

Elemental unit rates

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oce - Elemental unit rates

- BQ rates- All-in unit rates applied to quantity

- Elemental unit rates- BQ rates- All-in unit rates applied to quantityAll in unit rates applied to quantityAll in unit rates applied to quantity

ForecastingForecasting

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These information would arise from an analysis of past project used to be These information would arise from an analysis of past project used to be

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oce updated to current cost using the cost

index for the proposed project.updated to current cost using the costindex for the proposed project.

ComparisonComparison

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To make a comparison between itemwith similar function between differentTo make a comparison between itemwith similar function between different

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design in order to make decisiondesign in order to make decision

ComparisonComparison

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To make a comparison between itemwith similar function between differentTo make a comparison between itemwith similar function between different

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design in order to make decisiondesign in order to make decision

BalancingBalancing

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Breakdown of cost into smaller unitsBreakdown of cost into smaller units

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various components of building in d ith th li t i t

ie. How money are allocated to thevarious components of building in

d ith th li t i t

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oce accordance with the clients requirementaccordance with the clients requirement

This is important for checking purposesThis is important for checking purposesp g p pand cost strategy for development which can be obtained from past project.

p g p pand cost strategy for development which can be obtained from past project.

AnalysisAnalysis

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MONITORFEEDBACK

Type of construction estimatesAlternatives estimating techniques

ALTERNATIVE ESTIMATING TECHNIQUESALTERNATIVE ESTIMATING TECHNIQUES

•Spot Items•Operational Estimating•Extension of Bills of Quantity•Prime cost of day works

Spot ItemsSpot Items

• A lump sum estimate of an item was calculated by doing some taking off from the approximate quantities and the unit rate

• The description of work within the bills are analyzedThe description of work within the bills are analyzed into its constituent operations and trades and estimated for costing purposes

• Upon having described the work and it is found to have• Upon having described the work and it is found to have a predominant trade, then a gang or operational assessment can be made on time, plant and material basis so that overall cost can be calculated This isbasis so that overall cost can be calculated. This is similar to the construction project management tools known as Work Breakdown System

Spot Items (cont’d)Spot Items (cont d)

• From the 3 previous method explained, the cost of labour, plant and t i l h ld b t d i d t th lmaterials should be separated in accordance to the general 

principle described for unit rates.• The work should have been inspected thoroughly at the site visit 

and where necessary a construction method aka method ofand where necessary, a construction method aka method of statement should be established

• Adequate allowances should be made for the following items;– Storageg– Temporary work including support– Access– Double handling– Small deliveries– Making good and;– Reinstatement

Operational EstimatingOperational Estimating

• In some cases, it is preferable not to use normal estimating d f l l ti th it f ti l it t i d iprocedure for calculating the unit for particular items contained in 

BQ• Estimator may prefer to consider the inter‐relationship of the 

trades involved in the whole operationtrades involved in the whole operation• This is frequently the case with R/C concrete structures, where the 

cost of placing concrete will depend on the ratio of formwork, reinforcement and concrete, the chosen method of placing concrete and the total duration of operation rather than the unit cost of placing individual sections or parts of the concrete. 

• Based from this method of estimating, the plant, labour and materials rate are calculated based upon the total quantity of workmaterials rate are calculated based upon the total quantity of work and the total time available to perform the task.

• Example of the calculation can be referred at Appendix 1 Lecture 5

Extension of Bills of QuantityExtension of Bills of Quantity 

• After all the net unit rates have been completed, te a t e et u t ates a e bee co p eted,the draft Bill should be totalled before the additions are made for project overheads and h ll h llother allowances. Such extensions are normally 

made with separate sub‐totals being produced for 4 basic elements namely the;for 4 basic elements namely the;– Labour– PlantPlant– Materials and– Domestic sub‐contractors

Extension of Bills of Quantity (cont’d)Extension of Bills of Quantity (cont d)

• Further sub‐total are usually produced of anyFurther sub total are usually produced of any discounts contained within the unit rate in respect of materials, plant, sub‐contracted items and PC Sums.

• The extension of the draft bill rates to produce net rates should be carried out in a manner to reduce clerical error and also to allow 

blih f i b l l iestablihsment of various sub‐totals relating to elements of the work or trades as necessary

Prime Cost of DayworkPrime Cost of Daywork

• The composition of the total day work charge will p y ginclude the following costs:– LabourMaterials and goods– Materials and goods

– Plant– Incidental costs, overheads and profit (this addition , p (will vary between labour, plant and materials

This rate usually used to calculate any additional or omission work that is not stipulated in the contractomission work that is not stipulated in the contract but causes delay to the contractors.

Details of its definition and sample of calculation can be referred in Appendix 2 Lecture 5referred in Appendix 2 Lecture 5

Reference and further readingsReference and further readings

• Ahamad Abdullah – Anggaran Kos KerjaAhamad Abdullah  Anggaran Kos KerjaBangunan,2nd Edition, Pearson Prentice Hall, 2011.

• Edition,Peurifoy,R.L and Oberlander, G.D. –Estimating Construction Costs, 5th  Edition Mc‐Graw‐Hill, 2002.

• Popescu, C.M, Phaobunjong, K, Ovararin, N –Estimating Building Costs, Marcel DekkerInc2003.